The use of band heaters is well known in the prior art, see U.S. Pat. No. 3,370,156 to Graves. One type of band heater uses resistance heating wherein a resistance heating wire or heater cable is encased in a metal sheath. The metal sheath is in contact with the item or material to be heated or a structure containing a material needed to be heated. These heaters are often referred to as belly-band, crankcase, compressor or sump heaters and are often times used to heat refrigeration compressors or air-conditioning compressors. The heater can employ a standard hose clamp or other type of clamping arrangement for attachment to the compressor. The standard hose clamp is cut in two pieces with each piece affixed (welded for example) to opposite ends of the heater's metal sheath. Assembly of the heater to the compressor is accomplished by engaging the two ends of the clamp as intended and then tightening the assembly around the selected compressor location. This type of heater construction can also be used for heating containers such as barrels, heating pipes, etc.
Another type of band heater is one that employs a resistance heating cable encased in a silicone band. Examples of these types of band heaters are shown in U.S. Pat. No. 6,557,620 to Oshimo and U.S. Pat. No. 8,581,157 to Springer et al. In these types of heaters, the elements used for coupling the ends of the band together are normally overmolded to the heating cable and some type of structure is employed in connection with the overmolded elements to link the ends together. Typically, the structure is a tensioning device that permits the band heater to be securely clamped to the structure to be heated.
A band heater made by Raychem employs zip ties as the structure to couple the band ends together. This band heater is not like the resistance wire band heaters described above because it employs a self regulating semiconductor type material housed by a metal braid and outer insulation and uses a ground wire. This type of heating cable is expensive, limited in temperature and application choices, and has limited available wattages. The zip tie elements connected to the ends of the heating cable are held in place with adhesive and heat shrink tubing. The heat shrink tubing used is high strength to assure the integrity of the connection between the heating cable and zip tie element, but this type of tubing is also very expensive.
Zip ties are well known connectors for securing things and like uses, see www.zip-tie.com as an example of such zip ties. In its common form, the nylon cable tie consists of a tape section with triangular teeth that slope in one direction. The head of the cable tie has a slot with a flexible device that irreversibly rides up the slope of these teeth when the tape is inserted. The pawl engages, the backside of these teeth to stop removal of the tape. Other types use hook and loop fasteners with one end of the tie having the hooks and the other end having the loops. One end is passed through the slot in the head of the tie and is secured to the other end by virtue of the hook and loop engagement. Still others are considered releasable or reusable by having an additional tab, which has the flexible device noted above on it. The tab can be manipulated to disengage the teeth of the tie with the flexible device to allow the end of the tie to be retracted back through the slot in the head of the tie to release the tension caused by the zip tie when tightened. An example of these types of ties is found at http://www.alliance-express.com/standard-releasable-ties.
The prior art silicone band heaters still need improvement in terms of minimizing expense and simplifying the connection of the band ends. The present invention provides an improved silicone band heater that is inexpensive to produce and offers great flexibility in terms of its connection and clamping to a structure to be heated.